Friction stir welding method

ABSTRACT

On a main shaft  30  of a numeric control type machine tool, a rotary tool  50  is installed. The main shaft  30  is not inclined. To a table  20 , a first member  70  and a second member  76  to be subjected to a welding are fixed. Against to an axial center of the rotary tool  50 , to incline a welding portion of the first member  70  and the second member  76  in a stated in which the table  20  is inclined, by rotating the table  20  and moving a portion to be welded against the rotary tool  50 , and the portion to be welded is carried out according to the friction stir welding. The above stated inclination is a necessary inclination for the friction stir welding. A ring shape or a circular shape (including a circular arc) friction stir welding can be carried out easily.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to a friction stir welding, for example, relates to a circular shape welding.

[0003] 2. Prior Art

[0004] As shown in Japanese application patent laid-open publication No. Hei 9-309164 (EP 0797043 A2), a friction stir welding method is a method in which by rotating a round rod (it is called as “a rotary tool”) which is inserted into a welding portion and moving the rotary tool along to a welding line, and the welding portion is heated, softened and plastically fluidized and is solid-stately welded.

[0005] The rotary tool is comprised of a small diameter portion (it is called as “a pin”) which is inserted into the welding portion and a large diameter portion (it is called as “a shoulder”) which is positioned at an outside of the small diameter portion of the rotary tool. The small diameter portion and the large diameter portion of the rotary tool have the same axis. The large diameter portion of the rotary tool is rotated.

[0006] In Japanese application patent laid-open publication No. Hei 11-197855, it is disclosed a welding method of a case in which a welding line of two members is a ring shape (a circular shape). After a start end and a finish end of a welding have overlapped, the finish end is finished in a ring shape inner portion or a ring shape outer portion of the welding line. Accordingly, a friction stir welding has finished and a rotary tool is drawn from a member to be subjected to the welding, a hole according to the small diameter portion (the pin) of the rotary tool is left on the member to be subjected to the welding. When a drawing position is a ring shape position to be welded, a problem in strength causes.

[0007] Further, the rotary tool comprises a small diameter portion which is inserted into a welding portion and a large diameter portion which is positioned at an outside of the small diameter portion, The rotary tool is inserted incliningly to the member. An inclination direction is inclined that in a moving direction (a direction to be welded) of the rotary tool a side of the small diameter portion of the rotary tool is positioned in a front portion from a side of the large diameter portion of the rotary tool. In other words, the rotary tool is inclined to a rear portion. The above fact is shown also in Japanese patent laid-announcement No. Hei 9-508073 (EP 0752926 B1).

[0008] In Japanese application patent laid-open publication No. Hei 11-197855, the inclined rotary tool is moved in a circular shape. It is difficult extremely to move the inclined rotary tool in the circular shape. To correspond to the various kinds of the circular shapes, it is considered that the welding is carried out using a numeric control type machine tool. In this machine tool, the member to be subjected to the welding is fixed to a table, on a main shaft the rotary tool is installed, the main shaft is inclined, and the main shaft is moved in the circular shape. However, to maintain a predetermined inclination angle of the main shaft in a circular moving direction, it is necessary to vary the inclination angle with moving in the circular, as a result a preparation of programs is not easily.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is provide to a friction stir welding in which a ring shape or a circular shape (a circular arc is included) of a friction stir welding method can be carried out easily.

[0010] The above stated object can be attained by a friction stir welding method, characterized in that fixing a first member and a second member on a table of a machine tool to which a rotary tool is installed on a main shaft, and against to an axial center of the rotary tool, and further against a direction in which the first member and the second member are welded, under a state in which the table is inclined, by moving a portion to be welded against the rotary tool by rotating the table, carrying out the portion to be welded according to a friction stir welding.

BRIEF DESCRIPTION OF DRAWING

[0011]FIG. 1 is a side view of a friction stir welding means of one embodiment according to the present invention;

[0012]FIG. 2 is a flow chart of a welding of one embodiment according to the present invention;

[0013]FIG. 3 is a plane view of a member before a welding;

[0014]FIG. 4 is a longitudinal cross-sectional view of FIG. 3;

[0015]FIG. 5 is a plane view of the members after a welding;

[0016]FIG. 6 is a V-V cross-sectional view of FIG. 5; and

[0017]FIG. 7 is a longitudinal cross-sectional view of the members which has cut off after the welding and is a corresponding view of FIG. 6.

DESCRIPTION OF THE INVENTION

[0018] A friction stir welding method of one embodiment according to the present invention will be explained referring to from FIG. 1 to FIG. 7. FIG. 1 corresponds to I-I cross-sectional view of FIG. 3. A reference numeral 10 indicates a numeric control type machine tool. In ordinarily, the numeric control type machine tool is called as a machining center. The machine tool comprises a table 20 for mounting a mater to be subjected to a processing (a member to be subjected to a welding), and a main shaft for processing member to be subjected to the welding. The main shaft 20 can be rotated. The machine tool of this embodiment according to the present invention is a lateral axis type, an axis direction of the main shaft 30 directs in a horizontal direction. A face of the table 20 for mounting (fixing) the member to be subjected to the welding directs substantially in the vertical direction. This face of the table 20 can be inclined. The table 20 can be inclined an axis of the table 20 at a center (this is substantially along to the horizontal direction). The table 20 can be rotated the axis of the table 20 at the center. With the inclination state of the table 20, forming the axis of the table 20 as the center, the table 20 can be rotated.

[0019] On a tip end of the main shaft 30, a cutting use rotary tool of a working aim as a machine tool or a friction stir welding use rotary tool 50 can be installed. Herein, the friction stir welding use rotary tool 50 is installed. A tip end of the rotary tool 50 directs in a side of the table 20. An axial center of the main shaft 30 and the rotary tool 50 directs in the horizontal direction. The rotary tool 50 is rotated according to the main shaft 30. A tip end of the main shaft 30 can move in an axial direction. Further, the main shaft 30 can move in a radial direction against the axial direction.

[0020] The machine tool has a tool stocking device comprised of cutting use plural rotary tools and plural direction stir welding use rotary tools, and an automatic exchange device for exchanging a desirable rotary tool between the tool stocking device and the main shaft.

[0021] To the table 20, a member to be subjected to a welding 70 is fixed according to a public known means. In the member 70, a circular shape recessed portion 71 is provided in the side of the main shaft 30. To an outer peripheral portion of the circular shape recessed portion 71, a step-wise portion 72 is provided. The step-wise portion 72 and an outer face from this step-wise portion are substantially flatly. This flat face is a rectangular direction against the axial direction of the circular shape.

[0022] On the step-wise portion 72 a circular shape plate cover 76 is overlapped. An outer face of the member 70 and an outer face of the cover 76 are the same face. A butted portion between a circular periphery of the cover 76 and a circular periphery of the step-wise portion 72 is carried out according to a friction stir welding. Accordingly, a portion 79 to be welded (the welding line) is formed in a ring circular shape. A reference numeral 79 b indicates a welding bead which is caused by the welding. The butted portion between the member 70 and the cover 76 is carried out intermittently according to a temporary arc welding. After the temporary arc welding, the member 70 is fixed to the table 20 and the friction stir welding is carried out. After the friction stir welding, a space formed by the recessed portion 71 and the cover 76 forms a cooling passage. An inlet and an outlet of the cooling passage are not shown in figure. The member 70 and the cover 76 form a part of a cooling machine. The materials of the member 70 and the cover 76 are aluminum alloys.

[0023] The table 20 can be rotated the center of the circular shape welding line 79 as a rotation center. The rotation center of the table 20 and the center of the circular shape welding line 79 coincide with. The rotary tool 50 fixed to the main shaft 30 can not move (rotate) in a circumferential direction of the welding line 79. The rotary tool 50 can be rotated only by the rotation of the main shaft 30. By the rotation of the table 20, the rotary tool 50 can be moved relatively with the welding line 79.

[0024] The rotary tool 50 fixed to the main shaft 30 is positioned in a position 50S which is one position in a horizontal direction of a welding line 79. In this position 50S, the table 20 is inclined against a relative moving direction of the rotary tool 50 during the friction stir welding time. The inclination direction is inclined in the above stated moving direction (the direction to be welded), the small diameter portion 52 side of the axial center of the rotary tool 50 is to position in a front portion from the large diameter portion 51 side of the rotary tool 50. When the table is made to the standard, in the rotation direction of the table 20, the small diameter portion 52 side of the axial center of the rotary tool is to position in a rear portion from the large diameter portion 51 side of the rotary tool 50. The inclination angel θ of the table 20 is three (3) degrees, for example. In FIG. 3 and FIG. 5, the-rotary tool 50 is positioned in one of the horizontal direction position 50S of the circular shape welding line 79, and since the table 20 is rotated in a right direction, an upper side of the table 20 (the member 70) is inclined against a lower side to separate from the rotary tool 50.

[0025] A welding manner of this embodiment according to the present invention will be explained. To the table 20 which is inclined with the above stated three (3) degrees, the member 70, in which the cover 76 is carried out according to the temporary welding, is fixed. The rotary tool 50 is positioned in a predetermined position 50S. With this state, by rotating (rotating on own axis) the main shaft 30, the rotary tool 50 is projected in the axial direction, and the small diameter portion 52 of the rotary tool 50 is inserted to the butted portion (50S). When the rotary tool 50 is inserted in a predetermined amount the projection is stopped. An insertion position of the rotary tool 50 is the position 50S in FIG. 3. The position 50S is a start point of the welding (a step S11).

[0026] Next, under the stated in which the inclination angle having the state the above stated three (3) degrees is maintained, the table 20 is rotated. The rotation direction of the table 20 is the left-rotation (a step S13). A center of the rotation of the table 20 is a center of the welding line 79. Accordingly, the rotary tool 50 is moved relatively along to the welding line 79 and the butted portion is carried out the circular shape friction stir welding. The reference numeral 79 b indicates a welding bead according to the above stated friction stir welding operation.

[0027] When the rotation of the table 20 is continued and even the table reaches to the position 50S in which the rotary tool 50 has inserted, namely even when the table 20 is rotated 360 degrees, the rotation of the table 20 is made to continue. Accordingly, from the start point 50S of the welding the friction stir welding is carried out again.

[0028] Next, when the table 20 is rotated in a predetermined angle 360 degrees+α, the main shaft 30 is moved in the radial direction (a step S15). Herein, the main shaft 30 is moved in an outer side of the circular shape welding line 79. The table 20 is made to continue the rotation. The inclination angle θ of the table is not varied. Accordingly, in the outer side of the circular welding line 79 an arc shape welding bead 79 c is formed. The inclination angle θ of the rotary tool 50 against the relative moving direction of the rotary tool 50 from the angle 360 degrees+a (from the main shaft 30 is started to move in the radial direction) must be the above stated three (3) degrees. Herein, since this portion is not regularly the portion to be carried out the friction stir welding, it can be dispensed without the regular friction stir welding.

[0029] When the rotary tool 50 has moved in a predetermined position 50E, the main shaft 30 (namely, the rotary tool 50) is retreated and the main shaft 30 is drawn from the member 70 and the welding line 76 (a step S17). The retreat position of the main shaft 30 is judged by requesting a move amount of the main shaft 30. The retreat position of the main shaft 30 is an inner side of an outer diameter of the member 70. In a position (the finish point of the welding) in which the rotary tool 50 is drawn from the member 70, a hole 55, which corresponds to an outer diameter of the small diameter portion 52 of the rotary tool 50, is left.

[0030] After the friction stir welding has finished, the member 70 is taken off, and according another machine tool the unnecessary portion of the member 70 is cut off. Herein, the member 70 of the outside of the circular shape welding line 79 is cut off and made to a circular shape (a step S21). A reference numeral 74 shown in FIG. 5 and FIG. 6 indicates a cut-off position. Since the hole 55 is opened in the finish point of the welding, this cut-off is removed by cutting off an outer peripheral portion of the member 70 according to a machine processing. Further, when to the welding portion since burrs are occurred and the recessed portions are existed, according to the face to be welding (an upper face in .FIG. 6) is cut off, if necessary. As a result, the hole 55 in the welding finish portion is removed, and the welding of the side to be welded becomes flatly, then a good product appearance can be obtained.

[0031] Accordingly, it is unnecessary to incline the rotary tool 50 and to move the rotary tool 50 in the circular shape. Using the machine tool which can not incline the main shaft 30 (the rotary tool 50), the friction stir welding can be carried out. Further, in a case where the main shaft 30 is enable to incline, a design of the program for maintaining the predetermined angle θ in the circular shape moving direction and moving is troublesome and high cost. However, according to the above stated embodiment, since the inclination is given by the table 20, with this state the rotary tool 50 is rotated, the design having the above stated high cost programs becomes unnecessary. Accordingly, according to the above stated embodiment according to the present invention, using the existing machine tool, the friction stir welding can be carried in a low cost and easily.

[0032] These cut-off are carried out according to the demands. The hole 55 in the finish point of the welding is penetrated by a drill machine and the like, and the hole can be formed a bolt use hole and the like. Further, the hole 55 is buried according to TIG (Tungsten Inert Gas) welding, and the side of the welded face is cut off. As a welding rod for the TIG welding the same material of the member 50 is used. Accordingly, a welding portion of the hole is hardly seen in the case of no coating.

[0033] To the side of the main shaft 30, an optical type sensor for detecting the position of the butted portion is provided, and according to a value of this optical type sensor the position of the main shaft 30 can be moved. The moving direction of the main shaft 30 is a rectangular direction against the moving direction due to the rotation of the table 20. Accordingly, even the accuracy of a first member (70) and the accuracy of a second member (76) in the butted portion (the joining line 79) have inferior, the axial center of the rotary tool 50 can be positioned in the center of the butted portion.

[0034] Further, the lines of the subject to be welded the welding are the ones for welding the circular shape, a ring shape free curved line, a non-ring shape circular line, and a non-ring shape free curved line. In the case of the free curved line, the table 20 can be rotated in the center of the circular arc of the welding portion as a center and the table 20 is moved in the linear shape. Since the machine tool is the numeric control type, corresponding to the various curved lines, the welding can be carried out easily. The hole 55 of the finish point of the welding in the case of the circular arc shape line will be buried according to the welding or the soldering. Further, it can adopt to a ring shape welding in which the welding line comprises linear four (4) sides. In this case, as to the welding of the four (4) sides, the table is moved linearly. As to the welding of the intersecting portions of the sides or the circular arc portions in the vicinity, the table 20 is rotated.

[0035] Further, not only the welding of the butted portion, but also a portion in which two members are overlapped can be welded. Further, it can employ a longitudinal type machine tool.

[0036] When the welding has finished in an inner side of the circular welding line, for example, the inner side member is removed according to a counter boring processing.

[0037] The rotary tool 50 is inclined against the moving direction, and the rotation for the relative move is carried out according to the table 20. Since the inclination of the rotary tool 50 and the circular move for the rotary tool 50 are separated, the welding can be carried out in the low cost and easily.

[0038] Further, after the carry out of the friction stir welding, under the state where the member 70 is fixed to the table 20, the rotary tool 50 of the main shaft 30 is exchanged to the cutting use rotary tool. The exchange is carried out according to an automatic exchanging device between the main shaft 30 and a tool stocking device. After that, according to the main shaft the cutting use tool is rotated, the unnecessary portion is cut off. After the cut-off, when the friction stir welding is carried out, the oil for the cutting and the oil for cleaning after the cut-off give a bad influence to the friction stir welding. Further, according to the residual stock removal the combination accuracy in the two members may become bad. However, after the carry out of the friction stir welding, since the unnecessary portion is cut off, the above stated problem can be removed. Before the friction stir welding, the cut-of the two members is carried out, however the removal of the cutting use oil is carried out sufficiently according to another machine. As the cut-off, for example, there are an enlargement with a desirable diameter of the hole 55 during the retreat of the rotary tool 50 time and further a screw cutting process.

[0039] Further, the friction stir welding of a pair of the members to be subjected to welding is carried out using a first rotary tool, next between the main shaft and the tool stocking device, the rotary tool is exchanged, next the friction stir welding of a second welding portion of the above stated members to be subjected to welding is carried out using a second rotary tool.

[0040] A technical range according to the present invention is not limited by the wordings defined in each claim of what is claimed is or the wordings stated on the means for solving the problems and further it refer also to the range in which the man belonged in this technical field can be placed easily.

[0041] According to the present invention, the ring shape, the circular shape, the free curved line, the circular arc shape friction stir welding can carried out easily. 

What is claimed is:
 1. A friction stir welding method, characterized in that installing a friction stir welding use rotary tool to a main shaft in which an axial center thereof directs in a horizontal direction or in a vertical direction, fixing a first member and a second member on a table which opposes to a tip end of said rotary tool; and in a direction in which said first member and said second member are subjected to welding, to position a side of a small diameter portion of an axis center of said rotary tool in a front portion from a side of a large diameter portion of said rotary tool, under a state an axis center of said table is inclined, by rotating said table, moving a portion to be subjected to welding against said rotary tool, and carrying out a friction stir welding to said portion to be subjected to welding.
 2. In a friction stir welding method according to claim 1 , the friction stir welding method characterized in that said machine tool is a numeric control type machine tool.
 3. In a friction stir welding method according to claim 1 , the friction stir welding method characterized in that during the friction stir welding, accompanying with a rotation of said table, moving linearly said table.
 4. In a friction stir welding method according to claim 1 , the friction stir welding method characterized in that during the friction stir welding, carrying out independently a rotation of said table and a linear move of said table.
 5. In a friction stir welding method according to claim 1 , the friction stir welding method characterized in that to a member for supporting said main shaft, providing a sensor for detecting said portion to be subjected to welding; to position said rotary tool in said portion to be subjected to welding of said first member and said second member, according to a detection value of said sensor, moving relatively said main shaft supporting member against said table.
 6. A friction stir welding method, characterized in that installing a friction stir welding use rotary tool to a main shaft in which an axial center thereof directs in a horizontal direction or in a vertical direction, fixing a first member and a second member on a table which opposes to a tip end of said rotary tool; and in a direction in which said first member and said second member are subjected to welding, to position a side of a small diameter portion of said axis center of said rotary tool in a front portion from a side of a large diameter portion of said rotary tool, under a state an axis center of said rotary toll is inclined, by rotating said table, moving a portion to be subjected to welding against said rotary tool, and carrying out a friction stir welding to said portion to be subjected to welding.
 7. In a friction stir welding method according to claim 6 , the friction stir welding method characterized in that said machine tool is a numeric control type machine tool.
 8. In a friction stir welding method according to claim 6 , the friction stir welding method characterized in that during the friction stir welding, accompanying with a rotation of said table, moving linearly said table.
 9. In a friction stir welding method according to claim 6 , the friction stir welding method characterized in that during the friction stir welding, carrying out independently a rotation of said table and a linear move of said table.
 10. A friction stir welding method according to claim 6 , the friction stir welding method characterized in that to a member for supporting said main shaft, providing a sensor for detecting said portion to be subjected to welding; to position said rotary tool in said portion to be welded of said first member and said second member, according to a detection value of said sensor, moving relatively said main shaft supporting member against said table.
 11. A friction stir welding method, characterized in that in a case where a first member having a ring shape end face and a second member being butted to said ring shape end face of said first member are carried out a friction stir welding, after a welding in a ring shape along to said butted portion, in an inner side or an outer side of a ring shape welding line, finishing the friction stir welding; and removing said finished inner side or said finished outer side according to a machine processing.
 12. A friction stir welding method, characterized in that after a first member and a second member have been welded in a ring shape according to a friction stir welding, finishing the friction stir welding in an inner side or an outer side of a ring shape welding line; and removing said finished inner side or said finished outer side according to a machine processing.
 13. A friction stir welding method, characterized in that carrying out a friction stir welding a first member and a second member using a friction stir welding use rotary tool; in at least one member of said first member and said second member, drawing up said rotary tool.
 14. A friction stir welding method according to claim 13 , characterized in that to said hold, using a substantial same material of that of said least one member, said hole is buried by carrying out TIG welding (tungsten inert gas welding).
 15. A weld body, characterized in that a first member and a second member are carried out in a ring shape according to a friction stir welding; the friction stir welding is carried out from a side of one face of said first member; and by continuing to said portion in which the friction stir welding has been carried out, in a radial direction outer side of said ring shape members, the weld body has a portion which is welded according to a second friction stir welding; and an end portion of said portion which is subjected to welding according to the second friction stir welding is positioned to an end face of a radial direction outer side or a radial direction inner side of said first member or said second member.
 16. A machine tool comprises: a table for enable to rotate a face for fixing a pair of members in a vertical face or in a horizontal face; and a main shaft opposed to said horizontal face or said vertical face and having an axis center along to a horizontal direction or a vertical direction and further enable to rotate under a state in which a friction stir welding use rotary tool is installed to a tip end thereof; the machine tool, characterized in that as to a direction of said table, in a rotation direction of said table, a side of a small diameter portion of an axis center of said rotary tool is positioned in a rear portion from a side of a large diameter portion of said rotary tool, and said axis center of said rotary tool is enable to incline.
 17. In a machine tool according to claim 16 , the machine tool characterized in that a tip end of said main shaft is installed to enable to move along to said axis center thereof.
 18. In a machine tool according to claim 16 , the machine tool characterized in that said main shaft is installed to enable to move in a radial direction of said main shaft during the rotation of the table.
 19. In a machine tool according to claim 16 , the machine tool characterized in that said table is installed to enable to move in a radial direction of said axis center thereof during the rotation of said table.
 20. A machine tool comprises: a table for enable to rotate a face for fixing a pair of members; and a main shaft in which an axis center is inclined against a horizontal face or a vertical face of said table and being enable to rotate under a state in which a friction stir welding use rotary toll is installed to a tip end thereof; the machine tool, characterized in that as to an inclination of said main shaft, in a rotation direction of said table, a side of a small diameter portion of an axis center of said rotary tool is positioned in a rear portion from a large diameter portion of said rotary tool, and said axis center of said rotary tool is enable to incline.
 21. A machine tool according to claim 20 , characterized in that a tip end of said main shaft is installed to enable to move along to said axis center.
 22. A machine tool according to claim 20 , characterized in that said main shaft is installed to enable to move in a radial direction of said main shaft during the rotation of the table.
 23. A machine tool according to claim 20 , characterized in that said table is installed to enable to move in a radial direction of said axis center during the rotation of said table. 